Clemson University TigerPrints All Theses Theses 5-2011 OPEN SOURCE RIGGING IN BLENDER: A MODULAR APPROACH Ryan Cushman Clemson University, [email protected] Follow this and additional works at: https://tigerprints.clemson.edu/all_theses Part of the Computer Sciences Commons Recommended Citation Cushman, Ryan, "OPEN SOURCE RIGGING IN BLENDER: A MODULAR APPROACH" (2011). All Theses. 1055. https://tigerprints.clemson.edu/all_theses/1055 This Thesis is brought to you for free and open access by the Theses at TigerPrints. It has been accepted for inclusion in All Theses by an authorized administrator of TigerPrints. For more information, please contact [email protected]. OPEN SOURCE RIGGING IN BLENDER: A MODULAR APPROACH A Thesis Presented to the Graduate School of Clemson University In Partial Fulfillment of the Requirements for the Degree Master of Fine Arts Digital Production Arts by Ryan Cushman May 2011 Accepted by: Dr. Donald House, Committee Chair Dr. Timothy Davis Dr. Brian Malloy ABSTRACT Character rigs control characters in the traditional CG pipeline. This thesis examines the rig creation process and discusses several problems inherant in the traditional workflow—excessive time spent and a lack of uniformity, and proposes a software plugin which solves these issues. This thesis describes the creation of a tool for Blender 3D which automates the rigging process yet keeps the creativity and control in the hands of the user. A character rig designed by this tool will be fully functional--yet capable of being split into its component parts and reconstructed as the user determines. These body parts are individually scripted with the intent of maximizing reusability, and the code and rigs are distributed to the open source community for vetting. The final tool has been downloaded many times by the Blender community and has met with very postive responses. ii DEDICATION I would like to dedicate this thesis to Sarah, my wife. She did not hesitate when I proposed to throw our lives in the air with a crazy plan to work in feature films. Instead, she made the entire process more of a joy than I can express. Through the good times and the rough, she has been on every side of me holding me up. iii ACKNOWLEDGMENTS First, I would like to thank my family—especially Sarah, who put up with odd discussions and even odder hours during the writing of this thesis. Thanks to Dr. Donald House, who provided much needed guidance and friendship. I would also like to thank my committee members, Dr. Davis and Dr. Malloy, for their time and help—in both this thesis and across my education. Several fellow students helped out in a big way, so I would like to say a special thank you to Zach and Tony. Without their expertise, this thesis never may have progressed beyond theory. Finally, thank you to the Blender community—especially Ton Roosendaal and the crew at “Blender Artists.” I could not have gotten any of this accomplished without the many things that they have accomplished in the past and the advice and criticisim that they provided as I worked. iv TABLE OF CONTENTS i. Abstract . ii ii. Dedication . iii iii. Acknowledgments . iv I. Introduction . 1 II. Background. 4 2.1 The History of Rigging and Animation . 4 2.1a: Rigging and Animation . 4 2.1b: Rigging Plugins . 7 2.2 History of Open Source Development . 11 2.3 The Rigging Process . 20 III. Methodology. 24 3.1 Choosing and Learning a 3D Package . 24 3.2 The Character Design Process . 27 3.3 The Rig Design Process . 28 3.3a The Legs and Feet. 29 3.3b The Arms and Hands . 33 3.3c The Spine . 34 3.3d The Face and Head. 37 3.4 Writing the plugin. 39 v 3.4a TheModules. 41 3.4b The Main Control Panel. 49 IV Evaluation . 54 V. Conclusion . 57 VI. Bibliography . 59 vi IMAGE INDEX Figure 1.1: “Mr. Potato Head” . 3 Figure 2.1: “Cockpit Simulation of The Human Factor” . 4 Figure 2.2 “A Two Gyro Gravity Gradient Altitude Control System”. 5 Figure 2.3: “The Skeletal Animation System” . 6 Figure 2.4: BlockParty Workflow . 10 Figure 2.5: FK Articulation . 21 Figure 2.6: Copy Location Constraints . 22 Figure 2.7: Control Objects . 23 Figure 3.1: Polygon Modes . 26 Figure 3.2: Armature Modes . 26 Figure 3.3: A Blender Bone . 27 Figure 3.4: Maya Joints . 27 Figure 3.5: The Design Process . 27 Figure 3.6: Stretchy Limbs. 30 Figure 3.7: Rubber Hosing. 31 Figure 3.8: Knee Correction. 31 Figure 3.9: The Foot Roll Control. 32 Figure 3.10: Leg and Foot Rig Overview . 32 Figure 3.11: The Clavicle Control. 33 Figure 3.12: The Finger Roll Control . 34 Figure 3.13: Bbone Properties. 35 Figure 3.14: Bbones Curving . 36 vii Figure 3.15: Bending and Stretching Spine. 36 Figure 3.16: Spine Rig Overview . 37 Figure 3.17: Facial Rig Overview. 38 Figure 3.18: Mouth Shape Controls. 39 Figure 3.19: Main Control Panel . 41 Figure 3.20: A Rig Module . 41 Figure 3.21: Control Panel Breakdown . 50 viii I. INTRODUCTION Character rigging is the part of the character creation pipeline between the modeling of the 3D character and the animation. Character rigs provide controls which dictate the animation of a character. Often thought of as a tedious and overly complicated process, rigging is necessary for even the most basic of animations. Without a rig, a 3D model is nothing more than a digital statue. For complicated scenes (such as crowd scenes), the rigging process can often bottleneck the entire production pipeline as artists must spend time rigging every character. Rigging is often considered to be a distasteful process for many reasons. For one, it involves tedious repetition of actions; in addition, it requires the implementation of solid logic and problem solving skills. Many rigs are extremely technical and operate as much by programing as manual character animation. The standard solution to these problems is to write a custom tool which simplifies the process and various attempts have been made at this over time. Many of the best rigging tools are the property of individual studios and cannot be used by outsiders. Of the remaining options, most are either expensive and/or lack functionality. The high price point is a direct result of the sheer effort that goes into maintaining a viable rigging tool. If it is going to have any flexibility or use in a pipeline, it needs a great deal of maintenance and development. This thesis demonstrates a plugin design that addresses functionality issues and also proposes a development format which allows maintenance to be carried on through the open source movement. A plugin created within the right community and released in 1 the right format can be more functional and useful than existing rigging tools. The challenge then comes from creating a logical structure for development which lends itself towards open source development and results in a product with all of the features and flexibility a useable rigging pipeline tool requires. This thesis attempts to begin the removal of much of the mundane tedium from rigging by providing a tool which can both streamline the rigging process for riggers, as well as making rigging accessible to modelers and animators. The goal is to create a plugin for a 3D package which initiates a "character body part library". In the end, every possible body part would be cataloged and a solid rig for that body part would be scripted. Once this point is reached, any character could conceivably be rigged by calling the right combination of these modules. A biped could become a faun by calling quadruped legs. A quadruped could become a centaur by calling a biped spine, arms, and a human face. A great analogy for the way this tool should work is the Mr. Potato Head children's toy (as pictured in Figure 1.1). When playing with this toy, children begin with a blank slate, and from this point they combine various body parts to create a wide variety of characters. If the child wants a different shape of mustache or arm, they simply switch it out from their box of spare body parts. With this workflow in mind, the plugin has been titled “Mr. Potato Rig.” 2 Figure 1.1 – “Mr. Potato Head” Image of Mr. Potato Head and Mr. Potato Head toy are the property of Hasbro Inc. The initial modules provided to users will be the individual elements required for a cartoony biped character. The idea is that as the open source community starts adapting the tool, they will add their new work to the release and the desired functionality and flexibility will be achieved through the efforts of many with minimal time by one. 3 II. BACKGROUND 2.1: The History of Rigging and Animation 2.1a—Rigging and Animation The term “computer graphics” was first used in the early 1960s. William Fetter of Boeing created a series of drawings entitled “Cockpit Simulation of Human Factor”. Shown in Figure 2.1, these drawings are 2D line drawings and bear very little resemblance to modern computer graphics, but they do demonstrate that even the earliest computer graphics simulations had to do with understanding the human form. In 1961, Edward Zajac from Bell Labs created the first computer generated film (pictured in Figure 2.2). His film was called “A two gyro gravity gradient altitude control system” and demonstrated that a satellite could be designed to always face the earth as it circled [5]. Figure 2.1: “Cockpit Simulation of The Human Factor” by William Fetter 4 Figure 2.2 “A Two Gyro Gravity Gradient Altitude Control System” by Edward Zajac The history of character rigging within the broader spectrum of computer graphics is a fairly convoluted story.